Trisomy 15

Hi Ladies. I recently had a missed miscarriage. I got back the results yesterday from the tissue that was analyzed after my d &c saying it was trisomy 15. I'm trying to figure out if this is a random occurance or if this could possibly be genetic? I do have one healthy 3 yr old and this was my first miscarriage. I have left a message for the nurse to call me back, but was wondering if anyone here has experienced something similar. Thanks!